1. Field of the Invention
The present invention relates to fields of pathology, immunology and molecular biology. More particularly, the present invention relates to a VH4 peptide signature in VH-expressing B cells that predicts and diagnoses multiple sclerosis.
2. Description of Related Art
B cells have historically been implicated in the pathogenesis of Multiple Sclerosis (MS) since elevated CNS immunoglobulins and oligoclonal bands were first described in MS patients in the 1940s (Kabat et al. 1950; Kabat et al., 1948). Additional evidence of B cell involvement in MS pathogenesis includes the presence of B cells in MS lesions (Raine et al., 1999), and presence of B cells trafficking into the CNS during lesion development (Esiri, 1977) that intensifies with disease duration (Ozawa et al., 1994). Furthermore, the ratio of B cells to monocytes is stable over the disease course, but those patients with a prevalence of B cells tend to have a more expeditious disease progression than those with monocyte predominance (Cepok et al., 2001). Antibodies in conjunction with complement have also been identified in MS lesions co-localized with disintegrating myelin, suggesting a potential causative role played by these immune elements in lesion development (Genain et al., 1999; Storch and Lassmann, 1997).
The inventor and others have shown that clonal expansion of B cells occurs in both cerebrospinal fluid (CSF) (Colombo et al., 2000; Monson et al., 2005; Owens et al., 2003; Qin et al., 1998; Ritchie et al., 2004) and lesion sites (Baranzini et al., 1999; Owens et al., 1998) of MS patients. Clones at different stages of affinity maturation can be found in the CSF, suggesting that expansion is local (Monson et al., 2005). This finding is further substantiated by evidence that both ectopic germinal centers (Magliozzi et al., 2004; Serafini et al., 2004; Uccelli et al., 2005) and centroblasts, specialized B cells only found in germinal centers (Corcione et al., 2004), can be detectable in the CNS of MS patients. Characterization of clonally expanded B cells from the CSF of MS patients (MSCSF) demonstrated that the antibodies these B cells express are often self-reactive towards antigens found in the brain (Qin et al., 1998; Lambracht-Washington et al., 2007).
Data from others have established that the VH4-expressing B cell population in particular harbors autoreactive B cells in both healthy controls (Koelsch et al., 2007) and patients with systemic lupus erythematosus (SLE) (Pugh-Bernard et al., 2001). For example, B cells utilizing the VH4-34 gene (formerly known as VH4-21) are often autoreactive towards sugars on blood cells and either undergo negative selection in the adult repertoire (Koelsch et al., 2007; Pascual and Capra, 1992), or class switch to the rare IgD isotype rather than IgG, presumably to dampen the response of these autoreactive cells in healthy individuals (Koelsch et al., 2007).
Autoreactive B cells from the CSF and brain lesions (i.e., CNS) of MS patients are not suppressed, but instead undergo extensive clonal expansion (Colombo et al., 2000; Monson et al., 2005; Owens et al., 2003; Qin et al., 1998; Ritchie et al., 2004; Owens et al., 1998; Lambracht-Washington et al., 2007; Harp et al., 2007; Owens et al., 2007). This observation may indicate that regulatory mechanisms in the CNS of these patients may be more flexible than they are in the periphery. However, the inventor's previous analysis of antibody repertoires from MS patient derived CSF B cells indicated that regulation of this population, as it relates to germinal center selection, is preserved (Harp et al., 2007). The exception to this finding is that some, but not all, individual clonal populations appear to be dysregulated, as evidenced by lack of mutational targeting (Monson et al., 2005). A number of independent laboratories have documented that VH4-expressing B cells are overrepresented in the CSF (Colombo et al., 2000; Monson et al., 2005; Owens et al., 2003; Qin et al., 1998; Ritchie et al., 2004) and brain lesions (Baranzini et al., 1999; Owens et al., 1998) of MS patients. This finding was inconspicuous, however, since clonally expanding and autoreactive B cells from the CSF of MS patients could be found utilizing variable genes from any of the heavy (and light) chain families (Buluwela and Rabbitts, 1988; Humphries et al., 1988; Kodaira et al. 1986; Lee et al., 1987; Shen et al., 1987).